In manufacturing industry, various resources are used in various processes for manufacturing products from raw materials, assembling parts to make products, or the like. In order to effectively utilize these resources or to appropriately adjust stock amounts, it is essential to create a production plan or a distribution plan to perform operation following this plan. The same is true not only in manufacturing industry but also in distribution business or the like.
However, on the site of product manufacturing or distribution, there exist numerous raw materials, intermediate products, and products, and resources for machining, transportation, or the like of them are associated with each other intricately. Accordingly, constraints which should be considered become complicated. Therefore, for example, it is uneasy to create a production plan or a distribution plan for keeping stocks appropriately or producing products without delaying the delivery date.
As a technology for solving such a problem, conventionally, scheduling apparatuses have been developed for rewriting a rule made by a person (for example, a rule to start production first from a product whose delivery date is closer) into a program, and creating the production plan or the distribution plan automatically.
Such a rule-based scheduling apparatus can make a certain kind of plan quickly even for a complicated problem. However, there are a problem that there is no proof for whether a mathematically optimum plan is really made or not, a problem that the rules become quite enormous, and the like.
Then, as such a rule-based scheduling apparatus, there is a technology described in Patent Literature 1. Patent Literature 1 discloses a technology which obtains a first measure corresponding to a difference between an end time and a scheduled end time of a series of processes obtained from a result of temporarily assigning processes to a resource, and a second measure obtained by digitizing compatibility between the temporarily assigned resource and the processes, and repeatedly corrects the temporary assignment until a best assignment result is obtained. In this manner, in the technology disclosed in Patent Literature 1, based on predetermined measures, correction to assign necessary processes to a resource is repeated. Thus, it is not ensured that a mathematically really optimum plan is made.
Accordingly, as a method to mathematically solving them, scheduling apparatuses creating a production plan or a distribution plan using mathematical programming have been developed.
By using the mathematical programming, it is possible to make a production plan or a distribution plan whose optimality is mathematically ensured. However, to make the production plan or the distribution plan according to this method, the planner needs to have high-level mathematical expertise. Thus, it has been often difficult for a general user who plans production and distribution handles such a scheduling apparatus creating the production plan or the distribution plan using the mathematical programming.
Accordingly, it is demanded to construct a system which allows even a general user who has no high-level mathematical expertise to simply make the production plan or the distribution plan in a form according to the mathematical programming.
As such a scheduling apparatus using the mathematical programming, there is a technology described in Patent Literature 2. Patent Literature 2 discloses that after a production plan is made by performing optimization calculation by the mathematical programming, a quantitative relation ratio is fixed between raw materials and products in this production plan, the amounts of the raw materials and the products are then corrected by using GUI (Graphical User Interface), and a production plan is remade with the amounts after correction and the quantitative relation ratio, thereby enabling a verification by which a planning result is not largely changed.
However, in the technology disclosed in Patent Literature 2, only a production plan specialized to specific operations can be made. Accordingly, by the technology described in Patent Literature 2, a general-purpose production plan or distribution plan cannot be made.
As a technology to make a general-purpose production plan or distribution plan according to a mathematical method by using the mathematical programming, there is AIMMS developed by Paragon Decision Technology B.V. This technology allows the user to define variables for the mathematical programming by using GUI, and formulate an objective function and a constraint expression by using the defined variables.
However, such technology requires the user himself/herself to input variables to be used in the mathematical programming one by one, and to describe also to write constraint expressions one by one as a mathematical expression. Accordingly, a general user who has no mathematical expertise cannot easily make full use of such technology.